银掺杂甘氨酸膜电极对食品中V_C的选择性测定

利用循环伏安法(CV)制备了薄而稳定的银和甘氨酸聚合物膜修饰电极,研究了VC在此电极上的电化学行为,建立了循环伏安法测定食品中VC的新方法。银和甘氨酸复合膜修饰电极对VC的电化学氧化具有明显的催化作用。在pH 5.0磷酸盐缓冲溶液(PBS)中,氧化峰电流(ipa)与其浓度(c)在1.6×10-6～3.0×10-3mol/L内呈良好的线性关系,线性方程为:ipa=-8.48×10-7+0.023 c(mol/L),相关系数为0.999 9;检出限为1.2×10-7mol/L。银掺杂甘氨酸膜电极可以消除食品中一些共存物质如VA、柠檬酸和苹果酸等的干扰,修饰电极具有良好的灵敏度、选择性和稳定性,试验中用于辣椒中VC的测定,结果满意。

Determination of Vitamin C in Food at Silver Doped Polyglycine Film Electrode

A silver doped polyglycine modified electrode was prepared to yield thin and stable polymeric films by cyclic voltammetry(CV).The electrochemical behavior of vitamin C at the modified electrode was studied.A novel method for determination of vitamin C using cyclic voltammetry was established.The modified electrode showed an excellent electrocatalytical effect on the oxidation of vitamin C.In pH5.0 phosphate buffer solution(PBS),the oxidation peak current versus the concentration of vitamin C showed a linear relations over the range of 1.6×10~-6~3.0×10~-3 mol/L with a correlation coefficient as follows:i_pa=-8.48×10~-7+0.023c(mol/L),R=0.999 9;the detection limit was 1.2×10~-7 mol/L.The recovery was 95.0%~101.0%.Major interferences such as vitamin A,citric acid and malic acid were tested at this silver and polyglycine compound modified electrode and found that selective detection of can be achieved.This new method has been successfully applied for the determination of vitamin C in cayenne with satisfactory results in this test.